宝石的力学性能.ppt

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Unit 27 Mechanical Properties of Gemstones,宝石的力学性能,1,、,Gemstones,may show,mechanical characteristics,as a result of the application of force,for example gemstones may be,damaged,broken,and,in some cases,be divided into two or more pieces,etc.,由于施加的力所致，宝石可能会表现出力学特征，如在一些情况下宝石可能被损害、破碎、被分成两片或者多片等。,Mechanical properties,involved in,gemology,are,cleavage,parting,and,fracture,hardness,density,.,宝石涉及到力学性能有断裂、分离和破碎、硬度、密度。,Cleavage,Parting and Fracture,断裂、分离和破碎,2,、,Cleavage,is the ability,possessed by some,gemstones,to split along certain,well-defined directions,leaving more or less flat faces(possibly showing pearly luster),lying parallel to crystal faces,even though crystal faces may not be present in particular,specimen,.,断裂是一些宝石具备的一种能力，可以沿着清晰的纹路分裂，留下的几乎是平面（可能显示出珍珠光泽），并与晶面平行，即使在一些特殊的样品中晶面了可能不会存在。,3,、,In certain minerals,this difference in strength is sufficient to,allow the crystal to split,parallel to the densely packed planes,when appropriate force is applied.,在一些材料中，当施加一定的力时，这些强度的差异足可以使晶体分裂，并平行于密排面。,This particular type of,splitting,is called,cleavage,is always,parallel to,an,ideal crystal face,and can only occur in a,single crystal.,这种特别的分裂类型成为断裂，总是平行于理想晶体面，并且只在单晶体中发生。,4,、,Because cleavage is a,directional characteristic,of,weak atomic bonding,any direction in a crystal,lying parallel to layers of atoms,is,a potential cleavage direction,although most minerals resist splitting along these,various planes,.,由于断裂是微弱原子结合的方向性特征，晶体中任何平行于原子层的方向都是潜在的断裂面，虽然大多数矿物质在这些不同位面的分裂会受到限制。,It is for this reason that cleavage is a highly,diagnostic feature,possessed to a,marked degree,by only a few,gemstones.,正因为如此，断裂是非常特有的特征，仅仅在为数不多的宝石中才会有。,5,、,When we refer to a gemstone with,noticeable cleavage,we need to discuss not only its direction,but also the,cleavage quality,.,当我们提到一个有明显解理面的宝石时，我们不仅需要讨论它的方向，还要讨论解理面的质量。,Citing the examples already given,diamond has,perfect octahedral cleavage,and graphite has perfect cleavage parallel to the,basal plane,(of the hexagonal crystal),called,basal cleavage.,引用已有的例子，金刚石具有完美的八面体解理面，石墨具有完美的与基面平行的解理面（是六面体晶体），称为基解理。,Other possible,directions of cleavage,include,rhombohedral,prismatic,pinacoidal,.,其他可能的解理面方向包括：斜方六面体、菱形、地面的。,Cleavage faces,may often be recognized by a series of very,shallow steps,where the break has occurred,along several layers of atoms,at the same time.,解理面经常可能经过一系列非常肤浅的程序进行验证，在解理面上同时会沿着原子的几层会发生破裂。,6,、,The,gemmologist,obtains benefit from,cleavage,because it is an aid to,identification,and the,cutter,obtains some benefit because,poor quality areas,can be removed easily from,rough materials,.,宝石学家获益于解理面，因为它可以有助于鉴定，同时切削也获得了一些益处，因为质量差的方面可以轻易的从原材料中去除。,While this,feature,is of particular importance to the,diamond cutter,there are probably more,disadvantages,than,advantages,associated with,cleavage,.,虽然对金刚石切削来说这种特征尤为重要，但是解理面的缺陷可能远大于优势。,It is virtually impossible to polish a gemstone parallel to a,cleavage direction.,实际上不可能将宝石抛光至于解理方向平行。,7,、,Parting,is the breaking or splitting along,lamellar twinning planes,.,裂理是沿着薄的孪生面的破坏或裂开。,Sometimes the,internal structure,of a gemstone causes a,physical effect,similar in appearance to cleavage.,有时宝石的内部结构会引起表面上看起来和解理相似的物理效应。,However,the gemstone breaks or splits along twinning planes.,但是，宝石是沿着孪生面破碎或裂开的。,For example ruby exists splits at,rhombohedral,and,basal directions.,例如，红宝石在斜方六面体和底部方向存在裂纹。,8,、,Fracture,is the random,non-directional,breakage,which occurs in most gemstones as a,result of,sharp impact,and is often considered to be a typical and identifying,feature of glass,.,破碎是任意的、无方向性的破坏，存在于大多数宝石，由于突然的作用力所致，经常作为玻璃的典型和标志性特征,。,Up to a point this is true,but it is also quite typical of,amorphous substances,in general,and of those crystalline materials that have no,pronounced planes of weakness,for example,quartz,or,beryl,.,在一点上这是正确的，但是它也是一般非结晶物质的典型特征，也是没有明显薄弱面的晶体材料的典型特征，如石英和绿宝石。,9,、,Several types of fracture,are recognized,those normally seen by the gemologist being,conchoidal,or shell-like.,破碎的几种类型已经是公认的，也就是那些通常被宝石学家看作贝克状的或类似贝克的。,When a mineral breaks with,curved concavities,then the break is called,conchoidal,fracture,from the,resemblance of the concavity,to the,valve of a shell,.,当一种矿物质破裂成弧形凹面，那么这种破裂称为贝克状破裂，因为破裂凹面相似于壳辨。,10,、,The,fibrous,tough structure of,nephrite jade,produces another kind of,fracture-hackly.,纤维状、坚硬的软绿玉结构产生另外一种类型的破碎,-,锯齿状的。,This refers to the,uneven,and often,jagged,break that occurs when this material is broken.,当这种材料破裂后，就会产生不规则的，并且经常是边缘粗糙的裂纹。,11,、,Other terms are used as earthy,splintery significance,for the in,mineralogy,to describe fractures such and uneven,but these has,little significance,for the,gemologist,.,其它的条件也被应用于描述这样的裂纹和不规则，如矿物学的泥土的、破裂意义，但是这些对宝石学家意义不大。,Hardness,硬度,12,、,Hardness is the ability of gem to,withstand abrasion,and is one of the,prime qualities,of,a gem material.,硬度是宝石的耐磨能力，是宝石材料的主要质量指标之一。,The scale of hardness,which is used universally for,gemology,and,mineralogy,is comparative one.,硬度等级是一个相对等级，广泛的用于宝石学和矿物学。,13,、,The,German mineralogist,Friedrich,Mohs,produced,practical scheme for hardness assessment,in 1822.,德国的矿物学家,Friedrich,Mohs,在,1822,年制定了硬度评价的实用方案。,After a number of,selection trails,he brought together,ten easily obtained minerals,which could be obtained,in a high degree purity,and listed them in order of ability to,withstand scratching,by other members of the group.,经过大量筛选，他把十种容易获得的矿物质放在一起，这些矿物质可以在高纯度下获得。团队的其他成员将这些矿物质依据他们的耐磨能力大小的顺序排列。,This resulted in which is now known as,Mohs,Scale of Hardness,.,以下就是这个实验的结果，也就是现在所为人知的莫氏硬度指标。,The scale in increasing order of resistance to abrasion is:,Talc 1 gypsum 2 calcite 3 fluorite 4 appetite 5 orthoclase 6 quartz 7 topaz 8 corundum 9 diamond 10,14,、,It is important to note that this is,only an,order of hardness,and that the difference in hardness between any two,adjacent members,of the scale is not an indication that a,uniform difference of hardness,exists between other pairs of members.,重要的是应该注意这不仅仅是硬度的顺序排列，并且指标中两相邻成员之间的硬度差异并不表示：其它成员对之间存在一个统一的差异。,But the,comparable hardness,of some,other common substances,would be noted,for example,finger nail,(2.5),window glass,(5-5.5),steel knife blade,(5.5-6),and steel file,(6.5-7).,但是某些其它常见物质的相对硬度应该引起注意，例如：指甲,2.5,，窗玻璃,5-5.5,，钢制刀片,5.5-6,，钢锉,6.5-7,Density and Specific Gravity,密度和比重,15,、,The,carbon atoms,that,unite to form either graphite or diamond,do so in different ways,not only producing difference,in hardness and cleavage,as described in the earlier section,but also differences,in their weight/volume ratios,which are termed as,density,.,碳原子以不同的方式形成石墨或者金刚石，不仅仅造成如前所述的了两者的硬度和解理的差异，也造成了体积,/,重量比率的不同，也就是密度。,16,、,The,density of every substance,including all gemstones,is determined by the,arrangement of its constituent atoms.,每一种物质的密度，包括所有的宝石，是由组成原子的排列决定的。,Density is measured by,the number of units of mass contained in 1 unit volume.,每一种物质的密度，包括所有的宝石，是由组成原子的排列决定的。密度是由一单位体积内的物质的质量的数值来表示。,Density=Mass/Volume,17,、,It is always expressed in,terms of units of weight and volume,e.g.,pounds/cubic feet,(,Ibs,/cu.ft.),grams/cubic centimeters,(g/cm,3,),kilograms/cubic meters,(kg/m,3,),There are other units used,particularly for liquids and gases,as such as,pounds/gallons,or,grams/,litres,.,总是以质量和密度的单位来表示密度，如磅,/,立方英尺、,(g/cm,3,),、,(kg/m,3,),，也有其它的单位，特别是对于也体和气体，如,g/l,18,、,The,density of a substance,is difficult to,test directly,so the term,specific gravity,is often used in gemology.,一种物质的密度很难精确测量，因此单词比重常用于宝石学。,Specific gravity,is the ratio,between the weight of a substance and the weight of an equal volume of water,at a temperature of 4C and at,standard atmospheric pressure.,比重是在,4,摄氏度和标准大气压下一种物质的重量和相同体积的水的重量之比。,